Streaming Media may be defined as listening or viewing media in real time
as it comes across the World Wide Web. With streaming technology, users
can watch and listen to media while it is being sent to their browser,
instead of waiting for it to completely download and then playing it.
Before streaming technology was available, a user might wait an hour (or
more!) to completely download a short media file.

In general, media
files are huge. For example, five minutes of uncompressed video would
require almost one gigabyte of space! So, when the audio and video is
prepared for streaming, the media file is compressed to make the file
size smaller. When a user requests the file, the compressed file is sent
from the video server in a steady stream and is decompressed by a steaming
media player on the user's computer to play automatically in real time.
A user can jump to any location in the video or audio presentation. Streaming
media generally tries keep pace with the user's connection speed in order
to reduce interruptions and stalling. Though general network congestion
is unavoidable, the streaming server attempts to compensate by maintaining
a constant connection.

Streaming Media
Player Required

Streaming technology
allows users to receive live or pre-recorded audio and video, as well
as "illustrated audio" (sound synchronized to still pictures). To access
streaming media, the user must have a player capable of displaying the
presentation. The College of DuPage uses Windows Media software to encode
streaming media. To access and view streaming media files, users must
have the free Windows Media Player.

Once the Windows Media
Player is installed, a user may simply click a link to a Windows Media
file. This prompts the player to launch automatically and begin playing
the requested file within seconds. Windows Media files can be linked like
any other file type; however, the most common way is to embed the file
in a Web page.

Terms and Concepts
to Know

Bandwidth:
A measurement of the amount of data that can be transmitted or received
in a specified amount of time. When discussing streaming media, bandwidth
is usually expressed in terms of bits per second (bps) or kilobits per
second (kbps). (Modems are rated in terms of kbps and usually abbreviated
as k. A 56.k modem has twice the bandwidth of a 28.8 k modem.)

Bandwidth is an important
consideration when dealing with streaming media. Simply put, more bandwidth
is required for more complex data. Therefore, it requires more bandwidth
per second to display a photograph that it takes to display text. When
delivering streaming media (large audio and video files), a great deal
of bandwidth is required to achieve an acceptable level of performance.

Server vs. Server-less
Delivery: Streaming media files is most efficiently delivered using
a dedicated streaming server. However, content may be uploaded and delivered
from servers other than a dedicated streaming server. Here is an example
of the same content delivered from a web server and the streaming video
server:Link 1 (web
server)
Link 2 (video server)
Depending upon the current activity of the web server, you may not have
noticed much of a difference between the two files. But, if there was
some network congestion on the web server, you probably noticed a great
deal of stalling. In contrast, there was probably little or no stalling
on the video server.

Another reason to
use the dedicated video server is space. The typical web server is configured
up to hold a great many HTML and graphic files, which are generally small.
The typical video server is configured with very large storage capacities,
as audio and video files may be huge. File size management is critical
since any server has a finite storage capacity.

Streaming:
Delivery of audio and video over the World Wide Web in real time. With
streaming technology, the browser can start displaying the data before
the entire file has been sent.

Unicasting:
Networking in which computers establish two-way, point-to-point connections.
This means when a user requests a file, and the server sends the file
to that user only. Unicasting allows a user to pause, or skip around in
a streaming media presentation. Because this method requires sending multiple
copies of the data to multiple users, bandwidth requirements are high.

Broadcasting:
To simultaneously send the same message to all users on the network. Broadcasting
sends a message to the whole network, whether or not the data is wanted.

Multicasting:
In contrast to broadcasting, where data is sent to the entire network,
multicasting sends a single copy of the data only to those users who request
it. Multiple copies are not sent across the network, nor is data sent
to clients who do not want it. This reduces bandwidth requirements, but
as a trade-off, users are unable to control the streaming media and thus
cannot pause or skip forward or backward in the presentation.

Webcasting:
Using the Internet to broadcast live or pre-recorded audio or video.

Embed: To place
the source within a document. The source cannot be edited.